(1) Field of the Invention
The present invention relates generally to an emergency air filtration device, and in particular to an air filtration device for use with a self-contained breathing apparatus (SCBA) of the type worn by fire fighters in the event that the SCBA malfunctions or becomes exhausted.
(2) Description of the Prior Art
Fire fighters and other emergency personnel entering burning buildings or toxic areas must carry an SCBA that includes a face mask, an air supply, a hose for connecting the mask to the air supply, and a regulator to control the flow of air from the air supply to the mask. The face mask in usually comprised of a clear visor that extends at least partially over the facial area of the user, with straps or other means to hold the visor onto user""s face. The mask includes a port, often in the visor, for connection of the mask interior to the air supply.
The regulator may be designed for connection directly to the mask. In this configuration, the regulator will include a connection fitting for use in connecting the regulator to the mask port, and a hose fitting for connecting the regulator to the hose. The front of the regulator is of a given configuration, which may vary by manufacturer and style. When the regulator is to be attached to the face mask, the regulator configuration is such that the regulator can easily be grasped by the user, who can determine the orientation of the regulator by feel. For example, the regulator may be generally circular and sized to fit within the user"" hand, even when gloves are worn. The regulator may include a thumb stop or other orientation locator, which may be either a projection or depression, to aid the user in determining regulator orientation.
There is always the danger that the SCBA may malfunction or the air supply may become exhausted during use. If so, the user has only a few seconds to reach safety or find a new source of filtered air. Since timely escape from a burning building or other toxic area may not be possible, the prior art has proposed the use of emergency filtration devices that can be carried by the user to replace the non-functional SCBA.
Generally, these prior art devices are comprised of a housing enclosing a filtration media, with the housing being adapted to replace the regulator or other part of the SCBA to connect the emergency filtration device to the face mask. For example, the emergency filtration device can include a fitting that is inserted into the mask port that normally receives the regulator. The filtration device is carried by the user, e.g., on the user""s belt, jacket, or other apparel. When the SCBA malfunctions, the user detaches the regulator, and then replaces the regulator with the filtration device.
Replacement of the regulator with the filtration device must be made under highly stressful conditions in which the user cannot breath and recognizes that he or she has only seconds before asphyxiation. Moreover, the user may be within a dark or smoky location that prevents the user from being able to visually observe the filtration device or the mask. Observation may also be prevented by the physical position of the mask relative to the user""s line of sight. Therefore, a filtration device that promotes ease of connection under these circumstance would be of great value, possibly preventing deaths due to the inability of the user to timely attach the filtration device.
The present invention is directed to an emergency air filtration device for use with a self-contained breathing apparatus. The invention relates especially to a filtration device that can readily replace the regulator in an SCBA in the event that the SCBA malfunctions, becomes empty, or is otherwise no longer functional.
Generally, the emergency air filtration device is comprised of a housing having an inner end and an outer end; a filter media within the housing; an attachment fitting at the inner end of the housing; and a front cover over the outer end of the housing. The front cover, which may also serve as a flame or fire shield to protect the filter media from open flame, has a configuration corresponding to the configuration of the cover or front plate of the regulator of the SCBA air pack with which the filtration device is adapted to be used.
That is, the front cover is of approximately the same size and shape as the front of the SCBA regulator, and includes projections or depressions that correspond to projections or depressions on the regulator cover. For example, both the front cover of the filtration device and the cover of the regulator may be generally circular with a thumb stop or other projection. By conforming the shape of the filtration device cover to the shape of the regulator cover, it has been found that the ability of the user to quickly replace the regulator with the filtration device is greatly enhanced, even when the user is unable to see the filtration device or the attachment port.
Generally, this enhanced ease of attachment is believed to be due to the ability of the user to utilize xe2x80x9cmuscle memoryxe2x80x9d. In xe2x80x9cmuscle memory,xe2x80x9d or xe2x80x9cmotor memory,xe2x80x9d certain movements are transformed as a result of repeated practice from a conscious action to an automatic action requiring no thought. In other words, a movement or series of movements practiced over a long enough period becomes automatic. This phenomenon is often used in athletic training and in military training, where an individual must learn to react quickly and automatically to a given set of circumstances without conscious thought.
Fire fighters and other SCBA users, through practice, becomes accustomed to the feel and manipulation of the regulator of the particular design of SCBA they are using, even under stressful and adverse conditions, and learn to manipulate the regulator without conscious thought. This trained ability to automatically manipulate the regulator by xe2x80x9cmuscle memoryxe2x80x9d is utilized in the present invention by positioning a cover on the front of the filtration device that has a configuration similar to the cover of the regulator. Thus, the user, who is already trained to manipulate the regulator, responds in the same manner to the filtration device, facilitating quick attachment of the device to the mask.
Various adapters can be positioned at the back of the device housing so that the filter can be used with different commercially available SCBA face masks. For example, a bayonet-type fitting can be used with filters designed for use with a Scott Air Pack.
Adapters for other port configurations are also possible, so long as the shape of the adapter corresponds to the shape of the port to permit an air-tight attachment. It will also be understood that the regulator can be attached at other positions in the SCBA. For example, the regulator can be positioned within the air hose between the air supply and the mask, or attached to the air supply.
The housing may be formed of two sections, while the adapter is formed of an annular fitting held in place when the two housing sections are brought together to form the filtration device housing. For example, the annular fitting may be held within an annular groove at the inner end of the housing. The housing may also include one or more one-way air exhaust valves so that expired air can be exhausted without going though the filtration media. Alternatively, these exhaust valves can be in the visor section or another part of the face mask.
Various types of filter media can be used in the filtration device, While the filter media may be comprised of a single material, a multi-layer media is preferably used, with each layer being adapted to remove a particular type of contaminant. For example, a three-layer filter media may include a particulate filter layer to remove particulates; an activated carbon layer to absorb harmful gases; and a carbon monoxide catalyst layer to convert carbon monoxide to carbon dioxide. The activated carbon layer is preferably formed of a solid bed of carbon for extended usage. A four-layer filter may also include a desiccant filter layer to remove moisture and thereby increase the effectiveness of the activated carbon and/or carbon monoxide catalyst layers.
The filter media may be packed within the filtration device housing, or the layers of filter material may be enclosed within a filter media housing to form a multi-stage filter cartridge, with the filter media housing being insertable within the outer filtration device housing. Contaminated air or smoke passes through particulate and desiccant filter layers, and then through the rear section that includes the activated carbon filter layers, and optionally the carbon monoxide catalyst filter layer.
In the event that a user of an SCBA realizes that the SCBA has malfunctioned or is empty, the user responding by trained reflexes, or xe2x80x9cmuscle memoryxe2x80x9d, quickly detaches the SCBA regulator from an attachment port, grasps the similarly-shaped emergency filtration device, and attaches the filtration device at the position where the regulator was previously attached. Since the section of the regulator grasped by the user has essentially the same shape as the shape of the filtration device cover, the trained response of the user enables the user to quickly attach the filtration device without needing to see where the device is being attached, and without fumbling to find the proper way to connect the device, losing precious seconds that could mean the difference between life and death.